1. Field of the Invention
The present invention relates to a dental safety syringe having a needle containment safety apparatus and method to protect medical personnel and others from the risk of accidental percutaneous needlestick injuries.
2. Prior Art
Because dental healthcare personnel are at risk of contracting diseases from accidental needle sticks a variety of safety syringes have been developed. Many of the safety syringes have a shield that is placed over the extended needle after medicine has been injected. For example Talonn et al. U.S. Pat. No. 5,522,812 has a shield that is manually placed over the end of an extended needle. Other shields are positioned by sliding a cylindrical shield down the body of the syringe, such as described in Stanners, U.S. Pat. No. 5,403,288. In such designs the hand of the person sliding the shield in place is close to the needle thereby providing some chance of a needle stick.
Another approach for providing a shield of protection from needle sticks is based on moving the extended needle in the proximal direction (retracting the needle) until the needle is contained within the cylindrical body of the syringe. Haber et al. U.S. Pat. No. 4,931,040 modifies the conventional carpule allowing a needle to be retracted and locked within the cylinder of the carpule. Because the Haber invention keeps a person""s hand at a greater distance from the extended needle than the above slidable shield devices, the chances of a needle stick are decreased. However the complex modifications to the carpule used by Haber may make the invention too expensive. Another example of retracting the needle within the syringe is described by Sak, U.S. Pat. No. 5,501,670 but requires a special and complex needle retracting unit.
Hence there is a need to provide an improved dental safety syringe for healthcare personnel that provides for safe disposal and has reduced complexity and cost.
A dental safety syringe that is adapted for use with existing conventional carpules and does not have the complexity of prior art safety syringes has been invented. The novel dental safety syringe of the present invention is easy to operate and an improvement over prior art devices.
In accordance with the present invention a dental syringe for dispensing medication from a carpule with a proximal slidable seal and a distal seal is comprised of a carpule carrier adapted for holding the carpule wherein the carpule carrier has external threads on the proximal end; a syringe assembly having a syringe body containing a slidable needle assembly wherein the syringe assembly has external threads on the proximal end and wherein the syringe assembly is adapted for receiving the carpule carrier, and a plunger assembly adapted for coupling to both of said external threads and having a means for retracting the slidable needle assembly safely inside the syringe body after medication has been dispensed.
A method embodiment of a dental safety syringe for use with a carpule wherein the carpule has a proximal slidable seal and a distal seal comprises the steps of providing a carpule carrier for holding the carpule wherein the carpule carrier has threads on the proximal end, inserting the carpule into the carpule carrier, attaching a plunger assembly to the threads of a syringe assembly, inserting the distal end of the carpule carrier in a syringe assembly wherein the syringe assembly has syringe body and a needle assembly, pushing the needle assembly so that a needle fully extends outside the syringe body and is in a condition for delivering medication, attaching the plunger assembly to the syringe assembly, delivering medication to target tissue; and retracting the needle assembly inside the syringe such that an accidental needle stick is not possible. When the plunger assembly is detached from the combination of the carpule assembly and the syringe assembly, the plunger is available for reuse. The combination of the carpule assembly and syringe assembly, where syringe body securely contains retracted needle, is in condition for disposal.